Feature/mobius for trees

[ron-wettenstein]

Motivation and Context

TreeExplainer now supports also the "Mobius" index.
Notes:

1. This branch was created from the feature/woodelf_stii_fsii_fbii branch. Both touch similar parts of the code and I wanted to avoid conflicts. So this PR include also the code added in Feature/woodelf stii fsii fbii #595. We should first merge the Feature/woodelf stii fsii fbii #595 PR and then review this PR.
2. I added Mobius to the supported indices of TreeExplainer. It is not part of the supported indices in the base Explainer class though. I do some casting when calling the super init. It this the right behaviour? Do we want to add Mobius to the base Exaplainer class, and maybe use the opportunity to support in in more explainers (It seems that in TabularExplainer Mobius will be easy to compute exactly but hard to estimate, lets talk about it).

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Public API Changes

• No Public API changes
• Yes, Public API changes (Details below)

TreeExplainer now support index="Mobius"

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How Has This Been Tested?

Manually and with tests. The test check the QuadratureTreeSHAP and IntervantaionalTreeSHAP implementation and compare it to Woodelf.

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Checklist

• The changes have been tested locally.
• Documentation has been updated (if the public API or usage changes).
• An entry has been added to CHANGELOG.md (if relevant for users).
• The code follows the project's style guidelines.
• I have considered the impact of these changes on the public API.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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